Real-Life Forensic Science

Unlike TV dramas, real forensic cases don't end in an hour.

Aug 11, 2005

Shortly before midnight on March 19, a heavyset 24-year-old man was standing outside a Mexican restaurant along West Arrow Highway in San Dimas, Calif., when a brawl broke out. No one is sure how the fight started in this small, affluent city east of Pasadena, but it came to a tragic end. The young man wound up on a stainless steel table in the Los Angeles County Coroner's Office, dead from multiple stab wounds.

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Like other victims of violent crime, as well as those who die inexplicably, the San Dimas man was sent to the coroner to be examined for cause of death. Details of such fatalities can become evidence critical to prosecuting--or exonerating--defendants in subsequent trials. The Los Angeles office performs about 6000 of these autopsies each year. One of nearly 4000 such facilities in the United States, it is second in size only to New York's.

Programs like CSI: Crime Scene Investigation--a regular atop the Nielsen ratings--have put the formerly obscure field of forensics at center stage. Since the prime-time drama exploded on the small screen during the 2000-2001 season, universities have been turning out ever-bigger crops of crime-fighting scientists. In 2000, the forensic program at West Virginia University (WVU) graduated four students. In 2004, some 500 students were enrolled.

In TV crime shows, investigators wrap up tidy, high-tech cases in record time, ending each workday with a dramatic arrest. And that kind of neat resolution is increasingly what the public has come to expect.

"People watch TV and get the impression that every tiny clue can be discovered, analyzed and sourced in an hour with absolute precision," says Dr. Max Houck, director of the Forensic Science Initiative at WVU, "and that really isn't the way the world works."

BODY SHOP

When I stop by the Los Angeles coroner's office, it's a good morning for a reality check: The loading dock, or "control area," is particularly busy. Some bodies are wrapped in sheets (arrivals), others in clear plastic (departures, bound for funeral homes or cemeteries). The San Dimas man started out here, too, where he was photographed and issued a matching green toe tag and plastic ID card that is imprinted on related documents. After a Live Scan machine digitized his fingerprints, his naked body--lying on a steel transport table--was wheeled to the crypt, to be preserved at a cool 42 F until a more extensive examination could be performed.

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By the time I catch up with him, the body of the San Dimas man is one of five corpses in a dark gray operating room, smelling faintly of natural body odor, plastic wrap and the preservative formalin. His steel table is locked perpendicular to a stainless steel drop-lipped sink, and tilted so that any bodily fluids flow toward the drain.

The position of coroner is typically a political appointment; medical examiners, who are physicians board certified in forensic pathology, conduct the actual autopsies. Their tools are not unlike those used by the great European pathologists of the late 1800s: scalpels, saws, forceps, clamps and large, sharp knives.

Ortiz-Colom inspects the San Dimas man's body and then makes a deep Y-shaped incision to access the internal organs, which he measures and dissects. Unlike his CSI counterparts, he does not recite a monologue of poignant observations into a voice recorder.

"With five autopsies at once, and the saws going and everyone talking, you wouldn't be able to hear a thing on the tape," says Craig Harvey, who oversees forensic autopsies as the chief coroner's investigator in Los Angeles. Instead, Ortiz-Colom uses an erasable marker to scrawl findings on the steel splash guard of the sink.

New technology promises to transform an ancient science.

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SPECTROMETERS: Have to identify a chemical, fast? Refrigerator-size Gas Chromatograph Mass Spectrometers have been reduced to the size of a suitcase (left) so that they can be used outside the lab. Also in the works is a laser-driven spectrometer capable of shaving minute layers of tissue for analysis.

MICROFLUIDICS: Need to place a suspect at a crime scene? Scientists are learning how to manipulate tiny quantities of fluid in a "lab on a chip." Soon, they will be able to place a drop of a sample containing DNA on a silicon chip, where it will travel through a network of capillaries that chemically identify the genes.

MICROEXTRACTION: Curious whether a drink has been tampered with? This technique uses thin optical fibers as "dipsticks" to obtain samples for analysis, eliminating the need for complicated preparation. More rugged versions of the delicate fibers are now being developed for field use.

SEROLOGY: Want to determine how long a bloodstain has been around? By using the decay rates of different types of RNA found in blood, forensic scientists may soon eliminate "I cut myself shaving last month" alibis.

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THE GAME OF CLUE

When the San Dimas autopsy is nearly over, criminalist Steve Dowell, who specializes in tool analysis, arrives bearing silicon-based dental-impression material. He spreads the red substance onto the knife wounds with a paint spatula and then waits for it to dry.

Back in his lab, Dowell will scan the molding's measurements into a database he is creating of wounds left by blunt and edged weapons. Already containing some 2000 images, the database will eventually be able to match, for instance, the width of wounds with various kinds of blades. It may also make autopsies more objective by identifying and correcting variations between medical examiners.

If the victim had been shot, Dowell might look for gunshot residue in order to rule out suicide. In such cases, he presses a small black disc covered with sticky tape against the victim's hands and inserts it into an electron microscope. If the unique X-ray signatures emitted by atoms in the sample don't match those of lead, antimony or barium--components of gunpowder--the person was probably murdered. "The purpose of physical evidence," Dowell says, "is to stand as a witness independent of everyone's stories."

In cases of a drug overdose or poison, the most important evidence comes from a prepared sample of tissue sent to the toxicology lab. There, scientists using a Gas Chromatograph Mass Spectrometer (GC/MS) can detect compounds, such as heroin or arsenic, that weigh less than a billionth of a gram.

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"The GC/MS is one of the most useful tools in forensics," says Rich Whipple, a chemist at the Lawrence Livermore National Laboratory in Livermore, Calif. "But using it to come up with answers is much more time-consuming than on TV. On CSI, a GC/MS may say a compound is Fuller Paint pink, but the real instrument would identify the chemical and then a scientist would have to piece together what it may be a component of. CSI is fun to watch," says Whipple, "but it's really Hollywood."

MADE FOR TV

Another common misconception is that every case requires DNA analysis. The reality: Because of its high cost, DNA testing often isn't used--even in some cases that might call for it. A report published with funds from the U.S. Department of Justice found that 540,000 criminal cases in the States still awaited biological evidence testing in 2004.

Even solid DNA evidence may not expedite an arrest. Though the National DNA Index System--which currently contains 2.4 million DNA profiles--will accept profiles provided for any convicted criminal, not all states consider the same crimes serious enough to warrant submission. Also, while some states have begun contributing DNA data from crimes committed before 1998, the year the index was established, others have not.

Because TV watchers sit on juries, it's only logical that dramatization of forensics would begin to affect trials. Heather Vitta, a forensic scientist in the biology and DNA unit of the Michigan State Police, worked on a case that was lost because a juror demanded irrefutable DNA proof. "We don't find biological evidence at every crime scene, and I shudder to think the public would consider it necessary to prove a case," she says. "It's sad, but now when I'm on the stand, prosecutors have to ask me how my work differs from CSI, just to address false expectations."

As for the San Dimas man, his case may never be solved. According to the Justice Department, even with the best forensic science there's only a 64 percent chance that an arrest will be made.

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